The present invention relates to a film material for film carrier manufacture and to a method for manufacturing a film carrier, and more particularly, to a film material used for manufacturing a film carrier for receiving a semiconductor chip thereon and to a method for manufacturing a film carrier using this film material.
Known methods for forming packaged semiconductor chips such as IC and LSI include a film carrier method. In this method, a conductive metal layer such as copper foil is formed on a film tape, the conductive metal layer is etched so as to form lead patterns whereby a film carrier is formed, and after connecting semiconductor chips to lead patterns on the film carrier by bonding, the film carrier is stamped and separated for each individual lead pattern so as to obtain film carrier chips each having a semiconductor chip mounted thereon.
FIGS. 4 and 5 show typical structures of the film carrier chips. First of all, FIG. 4 shows a bonding wire type of film carrier chip wherein a semiconductor chip and the lead pattern of a film carrier are connected with bonding wires. On a film 110 such as a polyimide resin film, a lead pattern 120 made of a conductive metal such as Cu is formed as a layer in a predetermined pattern. After a semiconductor chip 130 is mounted and fixed to the film 110 with solder, each electrode thereof and the lead pattern 120 are electrically connected with bonding wires 140. The peripheral portion of the semiconductor chip 130 is covered with sealing resin 150.
Next, FIG. 5 shows a bump type of film carrier chip wherein the semiconductor chip and the lead pattern of the film carrier are connected with bumps. The difference of this structure from that shown in FIG. 4 resides in that the lead pattern 120 extends to each electrode on the rear face of the semiconductor chip 130, and the lead pattern 120 and each electrode are electrically connected through bumps 170 made of Au or solder such that the semiconductor chip 130 itself is fastened to the film 110.
When these film carrier chips are compared with each other, the bonding wire type of film carrier chip has a problem in that it takes considerable labor to connect respective electrodes of the semiconductor chip 130 to the lead pattern 120 with the bonding wires 140. Further, since it is necessary to leave a sufficient distance between adjacent electrodes for performing the wire bonding operation, the distance between electrodes and the overall planar dimensions of the semiconductor chip 130 become relatively large. Furthermore, since the bonding wires 140 project from the surface of the semiconductor chip 130, the sealing resin 150 must be relatively large to completely cover the entirety of the bonding wires 140, whereby the overall dimensions of the film carrier chip are relatively large.
On the contrary, in the case of the bump type of film carrier chip, all connections can be made at one time by locating the bumps 170 between the electrodes of the semiconductor chip 130 and the lead pattern 120 and applying heat and pressure collectively, constituting an extremely efficient connecting operation. Furthermore, since the connection can be made even if the spacing between the electrodes is narrow, it is possible to have a small interelectrode electrode distance, that is, to use this technique with a small semiconductor chip 130. Since the bumps 170 are hidden below the rear surface of the semiconductor chip 130 and are thin, the bump type of film carrier chip has a relatively small thickness. As a result, it is possible to produce a film carrier chip having small overall dimensions.
For the above-mentioned reasons, the bump type of film carrier chip is considered to be superior to the wire bonding type of chip and so it is more widely used.
However, the bump type of film carrier chip has a defect in that it lacks adaptability to the electrode arrangement of the semiconductor chip 130.
Namely, the outer portion 121 of the lead pattern 120 of the film carrier chip 130 can be connected to external circuits, such as those of a printed circuit board, as is, as long as it has predetermined standard dimensions. However, since the electrode arrangements of the semiconductor chips 130 may differ, the inner portion 122 of the lead pattern 120 will have to be formed in advance in accordance with the electrode arrangement of the semiconductor chip 130, that is, the arrangement of bumps 170.
For this reason, films 110 provided with the same lead pattern 120 having an inner portion 122 of a predetermined pattern, namely, the same type of film carrier cannot be utilized for mounting semiconductor chips 130 having different electrode arrangements. And, for each different electrode arrangement of the semiconductor chips 130, it becomes necessary to manufacture a new film carrier provided with a lead pattern 120 of a different form. Furthermore, when the form of the lead pattern 120 is changed, masks and molds for etching have to be prepared for the different respective patterns, resulting in increased equipment costs, the need for retooling for each change in the pattern, and increases in production time.
Particularly, in recent years when the number of different electrode arrangements of the semiconductor chip 130 has increased and systems for producing few-of-a-kind parts have become prevalent, it has been a serious problem to provide a long lead time for the preparation of etching masks etc. according to each change in product, resulting in initial cost increases.